#define  _CRT_SECURE_NO_WARNINGS  1
#include <stdio.h>
int max3(int a, int b, int c)
{
    int max = a;
    if (b > max)
        max = b;
    if (c > max)
        max = c;
    return max;
}
int main()
{
    int a = 0;
    int b = 0;
    int c = 0;
    scanf("%d %d %d", &a, &b, &c);
    float m = ((float)max3(a + b, b, c) / (max3(a, b + c, c) + max3(a, b, b + c)));

    printf("%.2f\n", m);
    return 0;
}